The present disclosure relates to an optical scanning device configured to form an electrostatic latent image on an image carrier and an image forming apparatus with the optical scanning device.
An image forming apparatus includes an optical scanning device configured to form an electrostatic latent image on a photosensitive drum capable of carrying an image. An exposure device serving as the optical scanning device may include a laser diode, a lens, a polygon mirror, a polygon motor, an fθ lens, and a fold mirror all of which are contained in a housing.
Laser light emitted from the laser diode is guided through the lens to the polygon mirror. Then, the laser light incident on the polygon mirror driven into rotation by the motor is reflected and deflected by the mirror surfaces of the polygon mirror, then passes through the fθ lens, and is then reflected by the fold mirror. Thus, the laser light is guided to the drum surface of the photosensitive drum rotating in a sub-scanning direction and scans the drum surface in a main scanning direction.
With the rotation of the polygon mirror, heat generated from the polygon motor may be unevenly distributed in the housing to cause a temperature gradient in the fθ lens and thus cause unevenness in refractive index of the fθ lens. To cope with this, a thermally conductive member may be disposed between a high-temperature portion and a low-temperature portion inside the housing to make the internal temperature of the housing uniform.
Alternatively, a metallic member may be disposed between a main frame of the image forming apparatus to which the exposure device is mounted and the housing of the exposure device. The metallic member is directly mounted to the main frame and changed in shape between the high-temperature portion and the low-temperature portion in the housing to give a difference in heat dissipation performance and thereby make the internal temperature of the housing uniform.